The final days of rancorous public debate over a $7 billion oil pipeline that would snake from Canada through the midsection of the United States have taken on an unexpected urgency this week, as the economic and environmental stakes of the massive project snap into focus at a time of festering anxiety about the nation’s future.

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A hearing on Tuesday in Glendive, part of the Montana dinosaur trail, drew supportive union workers outside who say the region needs the jobs.

The round of public hearings by the State Department — stretching along the proposed pipeline route from a community college gymnasium here on Tuesday in eastern Montana, through Nebraska and Oklahoma to the Texas Gulf Coast — is ostensibly meant to focus on a single question: Is the pipe in the national interest?

Addressing that question, though — especially in the sprawling sweep of six huge states through which the pipeline or its pump stations would run like a spine — takes in a universe of conflicting, interlocking issues, from short-term economics to global climate, from the discontent of a rural belt losing population to issues of national energy security, joblessness, corporate power and prices at the corner pump.

Many of the hundreds of people who have attended the meetings — one on Thursday night in remote Atkinson, Neb., is expected to double the town’s population of about 1,200 — said they felt they were making a kind of last stand.

“We need the jobs, it’s that simple,” said Bret Marshall, 53, a laborer’s union worker who said he hoped to get work on the line and drove more than 700 miles across Montana to be here for Tuesday night’s hearing.

The State Department concluded last month that the project, Keystone XL, would cause minimal environmental impact if it was operated according to regulations, and the operator, TransCanada, has said the nearly 2,000-mile line would create 20,000 jobs in the United States. Opposition groups around the country, though, said the federal study did not consider the effects of a major spill, while supporters said the nation’s economy had continued to worsen, making Keystone XL all the more crucial.

The politics has fractured along unexpected lines. Here in Montana, Gov. Brian Schweitzer, a Democrat, strongly supports the project, while in Nebraska, Gov. Dave Heineman, a Republican, and both United States senators, one a Democrat, the other a Republican, have called for the line to be rerouted because of concerns about the Ogallala Aquifer, a crucial water source beneath the Great Plains.

The public meetings along the pipeline route end this week and come on the heels of a summer’s worth of protests against Keystone XL in front of the White House, which led to the arrests of more than 1,000 people.

Groups like the National Wildlife Federation, while conceding that the Obama administration seemed to be leaning toward approval, gathered local organizations to speak out this week — from conservationists to ranchers — hoping their impassioned concerns would give Washington pause. The State Department is expected to decide by year’s end whether to give the project its final approval, allowing it to proceed.

“The whole policy debate has dramatically increased in stature from a year ago,” said Anthony Swift, a policy analyst for the Natural Resources Defense Council, which is against the pipeline. “People would not be protesting, let alone getting arrested, for something that is a foregone conclusion.”

In Nebraska, controversy over Keystone XL has even managed to envelop the state’s beloved college football team.

This month the University of Nebraska’s athletic director, Tom Osborne, who is a former Republican congressman, pulled TransCanada’s sponsorship of a video that ran on big screens during two home games. The video paid homage to a former Cornhusker offensive line known as “the Pipeline,” and featured TransCanada’s logo.